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Remote stopped working; lots of beeping; what's up?

Discussion in 'Gen 3 Prius Main Forum' started by Johnny Cakes, Feb 5, 2017.

  1. Johnny Cakes

    Johnny Cakes Senior Member

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    Today I needed to run the 12v for a couple of hours while I was away from the car. I left the car in READY mode and locked the door with the hard key. I left with the remote (and hard key) and came back a couple of hours later.

    Now, the remote no longer works. If the door is open, then the car beeps inside non-stop. If I get out and close the door, it beeps outside three times. I have the key with me when I get out. It is NOT in the car. I only have one key.

    Any idea what is going on or how to fix it?
     
    #1 Johnny Cakes, Feb 5, 2017
  2. saltdiscus

    saltdiscus Member

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    Try resetting the car by removing 12 volt battery and see if that works.

    Posted via the PriusChat mobile app.
     
    #2 saltdiscus, Feb 5, 2017
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  3. Kramah313

    Kramah313 Active Member

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    If you really left it on the 12V (on or accessories on a normal car?), I would say your 12V is probably dead. The 12V battery is small and not able to handle a load without the traction battery recharging it for a long time. But then you mentioned it was in READY mode, which would indicate the car was actually started, probably with the engine cycling on and off to recharge the traction battery. This should have done nothing more than run off some of your gas.

    So it almost sounds like your key fob battery is dead. That's my guess, or that the 12V is low and the smart key system is going haywire as a result. To test if your key fob battery is dead, try holding the key fob right up to (within a centimeter) of the start button as you try to start the car.
     
    #3 Kramah313, Feb 5, 2017
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  4. bisco

    bisco cookie crumbler

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    maybe you didn't leave it in ready. nevertheless, time to test the 12 volt.

    btw, what were you doing, that required the 12 volt to be left on? even in ready, it's possible to kill it if the draw is too deep.
     
    #4 bisco, Feb 5, 2017
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  5. Johnny Cakes

    Johnny Cakes Senior Member

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    I needed to recharge my iPad, so I left the car in ready mode so that it could start occasionally to recharge the traction battery.

    I guess that brings up a more fundamental question: I thought that the 12 volt battery was primarily for starting the engine and pretty much everything draws power from the traction battery which is charged from the engine (and regenerative braking).

    Is that wrong? Does the 12 volt accessory plug run directly from the battery? If so, then it would be possible to run down the battery such that the car would not start. Is that correct?

    I have been thinking that in ready mode, as long as you had gas, you would never come back to a dead battery from a load on the 12 volt accessory plug.
     
    #5 Johnny Cakes, Feb 5, 2017
  6. mrbigh

    mrbigh Prius Absolutum Dominium

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    Lets recapitulate your phrase, are you sure you left the vehicle in Ready mode with the certainty that the engine will turn ON?
     
    #6 mrbigh, Feb 6, 2017
  7. Johnny Cakes

    Johnny Cakes Senior Member

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    Yes, everything is fine with the car battery.

    I am wondering whether a 12v load from the accessory plug COULD ever run the battery down or whether in ready mode the car would always protect itself from that by starting the engine and recharging assuming it had gas.
     
    #7 Johnny Cakes, Feb 6, 2017
  8. Kramah313

    Kramah313 Active Member

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    The 12V battery runs everything except for the a/c and the electric motors as far as I know. It is recharged from the traction battery instead of alternator like a regular car. So I guess it could be possible if the draw from the 12V is greater than what the traction battery is putting back into it. Maybe as the traction battery gets low it is unable to put as much charge back into the 12V?

    I didn't know that could happen either, I would expect the car to cut the charge to the 12V plug if this happened. But maybe it only does that if the USB plug consumes too much power.
     
    #8 Kramah313, Feb 6, 2017
  9. mrbigh

    mrbigh Prius Absolutum Dominium

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    Usually a cell phone doesn't draw more than 2 Amps at any given time
     
    #9 mrbigh, Feb 6, 2017
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  10. Johnny Cakes

    Johnny Cakes Senior Member

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    Let me see whether I have this correct.

    12v accessory outlet draws from the 12v car battery.
    The car battery is charged from the traction battery.
    If the traction battery gets low, the ICE will start to charge the traction battery (assuming READY mode and gas)

    Based on this, the 12v car battery should never be depleted due to a load from the 12v accessory outlet. Is that right?
     
    #10 Johnny Cakes, Feb 6, 2017
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  11. Kramah313

    Kramah313 Active Member

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    Don't iPads draw more though?
     
    #11 Kramah313, Feb 6, 2017
  12. mrbigh

    mrbigh Prius Absolutum Dominium

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    1 NOT, the 12v accessory outlet draws from the Hybrid System Inverter
    2 The car battery is charged by the Hybrid System Inverter
    3 YEsss
     
    #12 mrbigh, Feb 6, 2017
  13. Johnny Cakes

    Johnny Cakes Senior Member

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    Thanks for the reply and correction. One clarification: Does the Hybrid System Inverter draw from traction battery?
    If so, that means that the 12v battery is irrelevant to the 12v accessory outlet?

    And the bottom line: Assuming gas in the tank, the 12v car battery should never be depleted due to a load from the 12v accessory outlet. Is that right?
     
    #13 Johnny Cakes, Feb 8, 2017
  14. Prodigyplace

    Prodigyplace Senior Member

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    The 12V battery boots the computer system, runs accessories , and closes the relay for the traction battery.
    The engine is started by MG1 which gets power from the traction battery.
     
    #14 Prodigyplace, Feb 8, 2017
  15. mrbigh

    mrbigh Prius Absolutum Dominium

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    1, at all times
    2, exactly
     
    #15 mrbigh, Feb 9, 2017
  16. Prodigyplace

    Prodigyplace Senior Member

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    mrbigh's answers are true when the car is in Ready mode.
    In other modes, the accessory outlet draws from the 12V battery without replenishment from the traction battery.
     
    #16 Prodigyplace, Feb 9, 2017
  17. mmmodem

    mmmodem Senior Taste Tester

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    So complicated. Let's just say this, you can safely leave your iPad plugged in to charge with car in READY mode. I've done it at a drive-in. It's fine. Once battery capacity drops to 2 bars on the HSI, the engine starts up and gets it to 5-6 bars. The cycle repeats every 10-15 minutes.

    What's not safe is owning 1 key. Making a second key costs a couple hundred dollars to program. Replacing your 1 key requires a trip to the dealer costing upwards of $1000. Go get a second key.
     
    #17 mmmodem, Feb 9, 2017
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